and theres more tutorials to come .
So yes this is pretty basic but its important and many people ask me to make it.
First : know what causes lag to low end devices (ask low device end users to help you for this)
Second : use a touch triggered toggle key in the beginning of your level and make it effect a free group for example 999
Third : Assign stuff that cause lag to said group (999 in the example)
Four (optional) : add text or other stuff that tells the player they are on low detail mode if they took the key ( or not if they didnt take it )


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Also this whole low detail thing is used first by funnygame as far as I know in his level Abyss because 2.0 was very laggy before 2.01 made the moving feature smoother for everyone (but still lags for some people)